Brake System Fundamentals

Question 1

A force of 800 N applies to a master cylinder with an area of 8.0cm². Calcualte the system pressure in kPa.

Answer 1

1000 kPa

Question 2

A brake system develops 350 psi on application. The force produced at a caliper piston with an area of 2.75 in² is:

a) 127.27 lb
b) 1227.27 psi
c) 962.5 lb
d) 962.5 psi

Answer 2

c) 962.5 lb

Question 3

A 2.5 cm diameter master cylinder is replaced with a 5.0 cm diameter master cylinder. The result is:

a) more pressure in the system
b) more force at the calipers
c) less pressure in the system
d) more force at the wheel cylinders

Answer 3

c) less pressure in the system

Question 4

One reason DOT 5 brake fluid is not recommended for ABS systems is because it:

a) has a higher boiling point
b) has a lower boiling point
c) harms painted surfaces
d) is not hygroscopic

Answer 4

d) is not hygroscopic

Question 5

The gylcol-based brake fluid that has the highest boiling point is _____________.

Answer 5

DOT 4

Question 6

The automotive brake system converts kinetic energy to heat energy through:

a) friction
b) hydraulics

c) electronics
d) air pressure

Answer 6

a) friction

Question 7

Why should brake fuild be stored only in a sealed container?

Answer 7

Becasue the fuild is hygroscopic

Question 8

What are the three (3) things that friction between two sliding surfaces depends on?

Answer 8

1) the amount of force pressing the two surfaces together
2) the temperature of the surfaces in contact
3) the coefficient of friction of the materials in contact

Question 9

Pressure in an enclosed liquid:

a) varies with the size of the container
b) varies with the shape of the container
c) acts with equal force on equal areas
d) acts parallel to the surface

Answer 9

c) acts with equal force on equal areas

Question 10

The wheel cylinders and calipers converts pressure developed in the system into:

a) heat
b) mechanical force
c) directional pressure
d) static friction

Answer 10

b) mechanical force

Question 11

The force that tends to resist motion between objects in contact is called ________

Answer 11

friction

Question 12

The energy forms primarily present in the braking system are _______ energy and ______ energy.

Answer 12

kinetic heat

Question 13

What is the law of conservation of energy?

Answer 13

Energy can neither be created nor destroyed

Question 14

What is kinetic energy?

Answer 14

The energy of a mass due to motion - depends on mass and velocity (speed)

Question 15

If two objects are travelling at the same speed, but object 1 has twice the mass of object 2, how much kinetic energy does object 1 have?

Answer 15

Object 1 would have twice the kinetic energy.

Question 16

If two objects are equal mass, but object 1 is travelling at twice the speed as object 2, how much kinetci energy does object 1 have?

Answer 16

Object 1 would have 4 times the kinetic energy as object 2

Question 17

What is conduction?

Answer 17

Heat transfer between objects in contact with each other.

Question 18

What is convection?

Answer 18

Heat transfer that applies to fluids (liquids or gases). It’s the movement of the fluid that is being heated due to a change in its density.

Question 19

What is forced convection?

Answer 19

Forced convection occurs when mechanical means aid fluid movement. - It is the primes cooling method in brake systems. It’s created using fins.

Question 20

What are air scoops used for?

Answer 20

they use the forward motion of the vehicle to move air over and through the brake components for cooling.

Question 21

What is infrared radiation?

Answer 21

a form of light energy. transfers heat without direct contact between objects.

Question 22

What is a heat sink?

Answer 22

a heat storage device (a large mass) used to help dissipate heat.

Question 23

What is friction?

Answer 23

The resistance to movement

Question 24

What is a coefficient of friction (COF)?

Answer 24

A number representing the relative amount of friction between two surfaces.

Question 25

What happens to the coefficient of friction between the brake linings and the drum/rotor as the linings heat up?

Answer 25

The COF goes down

Question 26

What is brake fade?

Answer 26

occurs when the lining and the drums or disc overheat so severely that the friction between them virtually disapperas.

Question 27

What is static friction?

Answer 27

the friction between two stationary objects

Question 28

What is kinetic friction?

Answer 28

The friction between two surfaces that have relative motion between them.

Question 29

What is regenerative (regen) braking?

Answer 29

during braking, a generator converts the vehicle’s kinetic energy ino electricl energy. The torque required to spin the generator slows the vehicle down and the energy produced charges a large storage battery.

Question 30

What is hygroscopic?

Answer 30

The ability to absorb moisture.

Question 31

In a brake system, the amount of force that the fluid pressure enerates depends directly on the amount of ___________ in the system and the the working _______

Answer 31

Pressure - Surface area

Question 32

What two units is pressure measure in?

Answer 32

Pascals (Pa) and pounds per square inch (psi)

Question 33

What is one Pascal?

Answer 33

the pressure developed when a force of one newton is applied over an area of one square metre. 1 Pa = 1 N/m²

Question 34

What is 1 psi

Answer 34

The force of 1 lb applied over and area of 1 in²

Question 35

What is the formula for pressure?

Answer 35

p = F / A

F = the force applied

A = the area of the reaction surface